JPH06130174A - Emergency reactor core cooling water injecting system for light water reactor - Google Patents

Abstract

PURPOSE:To ensure safety by injecting cooling water smoothly and quickly by passive operation in case of level drop of primary cooling water thereby covering the reactor core with water. CONSTITUTION:The cooling water injecting system comprises control valves 13A, 13B provided for a water supply piping 12A and a pressure equalizing piping 12B communicating liquid shape parts A, C and gas phase parts B, D of a reactor pressure vessel 1 and a water supply tank 11, respectively, and a valve operating means 14. The valve operating means 14 comprises an elevating/lowering tank communicated with the liquid phase part A and the gas phase part B in the pressure vessel 1, means for supporting the elevating/ lowering tank, and a valve driving section for opening the control valves 13A, 13B at time of upward movement of the tank.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emergency core cooling water injection device for a light water reactor, and in particular, when the water level of the primary cooling water is lowered, the cooling water is passively operated to inject the cooling water into the reactor. It is related to the technology for ensuring safety.

[0002]

2. Description of the Related Art Emergency core cooling system equipment is used to maintain the submerged state of the core by injecting primary cooling water into the reactor pressure vessel when a primary cooling water loss accident occurs. , High pressure injection system, low pressure injection system, automatic decompression system, etc.

In these facilities, an abnormal drop in the water level in the reactor pressure vessel is detected by a water level measuring device, an electric signal is output, and power such as electricity or pneumatic pressure is supplied by this electric signal to open the valve. The cooling water (or boric acid water) is injected into the reactor pressure vessel from the emergency cooling water tank. Therefore, in an emergency, it is necessary to secure a device for signal transmission and a device that operates by power, and a reliable power source for reliably operating the emergency core cooling system.

In recent years, with the aim of simplifying the reactor system, there has been a demand for the development of a reactor based on a new idea that largely incorporates a passive safety system. The passive safety systems used in these reactors seek to ensure the achievement of safety functions by their own mechanism without external energy or signals or manipulation.

As a technique related to a passive safety system, Japanese Patent Application Laid-Open No. 62-108192, "Light Water Cooled Reactor" has been proposed. To explain the outline of the technology,
In the upper position of the reactor pressure vessel, a water supply tank for the emergency water supply system is connected in series, and a control valve that opens the pipeline when the discharge pressure of the pump drops when the emergency water supply system is installed, A part of the primary cooling water or boric acid water that is flooding the core is kept sucked by the pump, the discharge pressure of the pump is directly transmitted to the control valve, and the emergency water supply system pipeline is closed, When gas suction phenomenon occurs due to the water level drop in the reactor pressure vessel and the pump discharge pressure drops, the control valve passively opens the pipeline to automatically supply cooling water and boric acid water. It was started to maintain the flooded state of the core.

According to this technique, when the reactor water level is lowered or the pump is stopped, the submerged state of the reactor core can be maintained by passively activating the submersible system to supply water. Become.

[0007]

However, in order to operate the pump, it is necessary to prevent the occurrence of a power failure accident of the drive source such as the electric motor during the operation of the reactor.
In the part that continuously rotates, there are still problems to be solved, such as maintenance of the part in order to ensure safety.

The present invention has been made in view of the above circumstances, and the safety of a nuclear reactor is ensured by passively opening the part that shuts off the cooling water supply system only by natural force to supply water. The purpose is to secure.

[0009]

[Means for Solving the Problems] Several means for solving the above problems have been proposed. The first means is arranged between a water tank arranged above the reactor pressure vessel, a liquid phase portion and a gas phase portion of the reactor pressure vessel, and a liquid phase portion and a gas phase portion of the water tank. A water supply pipe and a pressure equalizing pipe for connecting them, a control valve arranged in the water supply pipe and the pressure equalizing pipe for opening and closing a pipeline, and a valve operation connected to the control valve for opening and closing the pipe. The valve actuating means includes an elevating tank connected to a liquid phase portion and a gas phase portion of the reactor pressure vessel, and the elevating tank is supported so as to be vertically movable and moves the elevating tank upward when the load decreases. An emergency core cooling water injection device for a light water reactor, comprising load supporting means and a valve drive unit interposed between the lifting tank and the control valve to open the control valve when the lifting tank moves upward. . The second means is an emergency core cooling water injection device for a light water reactor, in which the load supporting means in the valve actuating means and the elastic member for receiving the weight of the lifting tank are arranged in addition to the first means. A third means is an emergency core cooling water injection for a light water reactor, in which the first or second means has a structure in which a valve mechanism in the valve actuating means is provided with a link mechanism for driving the control valve in the opening direction. The device. A fourth means is an emergency for a light water reactor, in which a structure in which an elongated hole and a pin in an engaged state for delaying the movement in the opening direction are arranged is provided at the connecting portion of the link mechanism and the control valve in addition to the third means. It is used as a core cooling water injection device.

[0010]

In the first means, since the gas phase portion and the liquid phase portion of the reactor pressure vessel and the elevating tank are in communication with each other, the internal water levels in the reactor pressure vessel and the elevating tank are at the same level. Become. When the water level in the reactor pressure vessel is in a normal state, a large amount of water in the lift tank is maintained, and the lift tank continues to be lowered due to its weight, and the control valve provides an emergency water supply system pipeline. Is continuously closed. When the water level in the reactor pressure vessel drops, the internal water level of the lift tank drops to the same level, the weight decreases and the lift tank rises, and the control valve is opened by the valve drive unit. The liquid phase part and the gas phase part of the reactor pressure vessel and the water supply tank are in communication with each other, water is supplied from the water tank to the reactor pressure vessel due to the head difference of the liquid phase part, and the flooded state of the core is maintained. Done. In the second means, in addition to the operation of the first means, when the upward driving force by the elastic force of the elastic member exceeds the weight of the elevating tank, the elevating tank begins to rise and control is performed. The valve is opened. In the third means, in addition to the actions of the first means and the second means, the driving force is transmitted from the valve operating means to the valve rod via the link mechanism. In the fourth means, in addition to the action of the third means, when the link mechanism starts moving, the force transmission is delayed at the connecting portion of the slot and the pin,
When the water level in the reactor pressure vessel exceeds the control limit, water is supplied to the reactor pressure vessel.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an emergency core cooling water injection system for a light water reactor according to the present invention will be described below with reference to FIGS. In each drawing, reference numeral 1 is a reactor pressure vessel, 2 is a reactor core, 3 is a primary system pipe, 11 is a water tank, and 1 is a water tank.
2A is a water supply pipe, 12B is a pressure equalizing pipe, 13A, 13
B is a control valve, 14 is a valve operating means, 15 is a lifting tank, 1
6A and 16B are communication pipes (siphon pipes), 17 is load supporting means, 18 is a valve drive unit, A is a liquid phase part, B is a gas phase part, C is a liquid phase part, and D is a gas phase part.

In the emergency core cooling water injecting apparatus in the one embodiment, the emergency cooling water is injected into the reactor pressure vessel 1 by utilizing the head difference regardless of the internal pressure, and the core 2 It is applied to those that maintain the flooded condition of.

As shown in FIG. 1, the emergency core cooling water injection device includes a water supply tank 11 arranged outside the reactor containment vessel 5 and at an upper position (high place), and a reactor pressure vessel. 1. Liquid phase part A and gas phase part B and water tank 1
A water supply pipe 12A and a pressure equalizing pipe 12B arranged in a connected state between the liquid phase portion C and the gas phase portion D in FIG.
A control valve 13 arranged in the middle of the water supply pipe 12A and the pressure equalizing pipe 12B for opening and closing the pipeline.
A and 13B, and a valve operating means 14 connected to the control valves 13A and 13B for opening and closing the control valves 13A and 13B.

As shown in FIG. 2, the valve operating means 14 corresponds to the height dimension T of the normal operating liquid level H and the lower limit liquid level L formed inside the reactor pressure vessel 1, for example And a communicating pipe (siphon pipe) 16A, 1 for connecting the lifting tank 15 having a large vertical dimension and the inside of the lifting tank 15 and the reactor pressure vessel 1 at two locations, an upper side and a lower side.
6B, load supporting means 17 for supporting the lifting tank 15 in a vertically movable state, and moving the lifting tank 15 upward when the load on the lifting tank 15 decreases, the lifting tank 15, and the control valve 13
A lift tank 15 is placed in a connected state between A and 13B.
And a valve drive section 18 for opening the control valves 13A and 13B when the control valve moves upward.

More specifically, the lifting tank 15
Since the internal pressure of the reactor pressure vessel 1 is applied to the communication pipes 16A and 16B, it is necessary that the communication pipes 16A and 16B have sufficient pressure resistance. Deformability (flexibility) is provided to such an extent that the vertical movement of the tank 15 is not hindered. The communication pipe 16A at the lower position is set such that the opening position on the inner side of the reactor pressure vessel 1 is below the lower limit liquid level L of the liquid phase portion A, and the communication pipe 16B at the upper position is The opening position is set near the normal operating liquid level H or in the gas phase portion B. Further, the communication pipe 16A at the lower position has an opening position near the inner bottom of the lifting tank 15, and the communication pipe 16B at the upper position has an opening position above the inside of the lifting tank 15.

As shown in FIG. 2, the load supporting means 17 is disposed between the lifting tank 15 and the support structure 17a and receives the weight of the lifting tank 15 to move upward when the load is reduced. It has a member 17b and an elevating guide 17c which is arranged around the elevating tank 15 to allow vertical movement and restrain horizontal movement to impart seismic resistance.

As shown in FIGS. 2 and 3, the valve driving section 18 is a link mechanism 18a arranged in a connected state between the lifting tank 15 and the valve rods 13d of the control valves 13A and 13B.
And the elongated hole 18b and the pin 18c which are in an engaged state and which are arranged at the connecting portion between the link mechanism 18a and the valve rod 13d, and when the lifting tank 15 is located below, the valve rod 13d Allows free movement in the vertical direction of the
When 5 moves upward, as shown by the chain line in FIG.
The link mechanism 18a and the pin 18c are set so as to pull up the valve rod 13d to open the control valves 13A and 13B.

As shown in FIG. 3, the control valves 13A and 13B have a valve seat 13b and a valve body 13 inside a valve box 13a.
c is arranged, and the valve rod 13 is pressed by the elastic force of the presser spring 13e.
The structure is such that the valve seat 13b is kept closed by pressing d and the valve chamber 13g is isolated from the outside by the seal portion 13f. The elastic force of the pressing spring 13e is such that the valve seat 13b can be kept closed when the normal internal pressure of the reactor pressure vessel 1 is applied.

In such an emergency core cooling water injection device, the lifting tank 15 is connected to the liquid phase portion A and the vapor phase portion B of the reactor pressure vessel 1 via the communication pipes 16A and 16B. Therefore, a liquid level having the same height as the liquid level of the liquid phase portion A is formed in the lifting tank 15.

Therefore, during normal operation of the reactor, the liquid phase portion A of the reactor pressure vessel 1 becomes the normal operation liquid level H in FIG. 2, and the lift tank 15 is almost filled with the primary cooling water. State, the elastic member 17b of the load supporting means 17 is elastically deformed by the weight of the lifting / lowering tank 15, and the link mechanism 18a of the valve drive unit 18 maintains the lowered position as shown by the solid line in FIG. To do. In this case, due to the existence of the elongated hole 18b, the force is not transmitted between the valve rod 13d and the link mechanism 18a.

On the other hand, when the liquid level in the reactor pressure vessel 1 is lowered due to a leak or the like caused by breakage of the primary system piping 3, the liquid phase portion 15a of the lift tank 15 is lowered in conjunction with this, and the lift tank 15 is lowered. Since the overall weight of the tank is reduced, the elastic force of the elastic member 17b causes the elevating tank 15 to slightly rise to a position where it is in equilibrium and then stop. When the amount of upward movement of the lift tank 15 is within the range of the elongated hole 18b of the valve drive unit 18, the upward movement of the valve rod 13d of the control valves 13A and 13B is not performed, so that the control valves 13A and 13B are opened. Water tank 11 and water tank 11
The internal pressure of the reactor pressure vessel 1 is not applied to the water supply pipe 12A and the pressure equalizing pipe 12B between the control valve 13A and the control valves 13A and 13B.

When a situation occurs in which the liquid phase portion A drops to the lower limit liquid level L, the total weight of the lifting tank 15 is significantly reduced, and the lifting member 15b pushes the lifting tank 15 up, and the chain line in FIG. As shown in FIG.
Moves upward, the valve rod 13d is forcibly lifted, the valve body 13c is separated from the valve seat 13b, and
Pipe lines of the water supply pipe 12A and the pressure equalizing pipe 12B are opened.

When the pipelines for the water supply pipe 12A and the pressure equalizing pipe 12B are opened, the pressure difference between the gas phase portion B in the reactor pressure vessel 1 and the gas phase portion D in the water supply tank 11 disappears, and Due to the difference in pressure between the two liquid phase portions A and C, the emergency cooling water such as boric acid water is sequentially injected from the water supply tank 11 into the reactor pressure vessel 1,
The flooded state of the reactor core 2 is maintained. In this case, the emergency cooling water is injected regardless of the internal pressure of the reactor pressure vessel 1.

In these emergency water supplies, a driving source such as electricity or air pressure is not used, the weight of the lifting tank 15 is reduced, the lifting force is raised, and the control valves 13A and 13B are opened by the link mechanism 18a. It is carried out passively by natural force such as operation, and is not affected by power failure.

[Other Embodiments] In the present invention, the following techniques can be adopted instead of the embodiments. a) By partially extending the link mechanism 18a of the valve drive unit 18 in one valve actuating means 14, both control valves 13A, 13 of the water supply pipe 12A and the pressure equalizing pipe 12B
Activate B. b) The elastic member 17b should be a leaf spring or a tension spring. c) A snubber or the like is provided between the lifting tank 15 and the support structure 17a to ensure vertical movement and earthquake resistance of the lifting tank 15.

[0026]

The emergency core cooling water injection device for a light water reactor according to the first aspect of the present invention has the following effects. (1) A control valve interposed in a water supply pipe and a pressure equalizing pipe for connecting a liquid phase portion and a gas phase portion of a reactor pressure vessel and a water supply tank to each other, and a valve operating means for opening and closing the control valve. Then, the valve operating means opens and closes the lifting tank connected to the liquid phase part and the gas phase part of the reactor pressure vessel, the load supporting means that supports the lifting tank so that it can move up and down, and opens the control valve when the lifting tank moves upward. By configuring the valve drive unit to operate, when the water level of the primary cooling water drops, the passive operation operates to equalize the pressure in the gas phase portion and to cool the cooling water based on the head difference. It is possible to smoothly inject the fuel into the reactor pressure vessel to bring the core into a flooded state and ensure the safety of the reactor. (2) In the case of emergency water supply, a drive source such as electricity or air pressure is not used, but it is performed passively by natural force,
Not affected by power outages. In the emergency core cooling water injection device for a light water reactor according to claim 2, the load supporting means of the valve actuating means is provided with the elastic member for receiving the weight of the lifting tank. The following effects are added to the injection device. By supporting the weight of the lifting tank by the elastic force of the elastic member, it is possible to easily detect a change in weight and reliably supply water. The emergency core cooling water injection device for a light water reactor according to claim 3 employs a configuration in which a link mechanism for driving the control valve in the opening direction is arranged in the valve drive portion of the valve actuation means. Alternatively, the following effects are added to the injection device of claim 2. By transmitting the driving force from the valve actuating means to the control valve via the link mechanism, it is possible to improve the freedom of connection distance and direction. In the emergency core cooling water injection device for a light water reactor according to claim 4, an elongated hole and a pin in an engaged state for delaying the movement in the opening direction are arranged at a connecting portion between the link mechanism and the control valve. By adopting, the following effects are added to the injection device of claim 3. By delaying the transmission of force at the joint, it is possible to easily set the liquid level until the water level of the reactor pressure vessel exceeds the control limit, and to quickly supply water to the reactor pressure vessel when necessary. .

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of an emergency core cooling water injection device for a light water reactor according to the present invention.

FIG. 2 is a front sectional view of a portion of the valve actuating means shown in FIG.

FIG. 3 is a front sectional view of a control valve and a valve drive section shown in FIG.

[Explanation of symbols]

 1 Reactor Pressure Vessel 2 Core 3 Primary System Pipe 11 Water Supply Tank 12A Water Supply Pipe 12B Pressure Equalizing Pipe 13A, 13B Control Valve 13a Valve Box 13b Valve Seat 13c Valve Body 13d Valve Rod 13e Presser Spring 13f Seal Part 13g Valve Room 14 Valve Operating means 15 Lifting tank 15a Liquid phase portion 16A, 16B Communication piping (siphon pipe) 17 Load supporting means 17a Support structure 17b Elastic member 17c Lifting guide 18 Valve drive part 18a Link mechanism 18b Slot 18c Pin A Liquid phase portion B Gas phase part C Liquid phase part D Gas phase part

Claims (4)

[Claims] 1. A feed water tank disposed above the reactor pressure vessel, and a liquid phase portion and a gas phase portion of the reactor pressure vessel and a liquid phase portion and a gas phase portion of the feed water tank, respectively. Water supply pipe and pressure equalizing pipe for connecting the control valve, a control valve disposed in the water supply pipe and the pressure equalizing pipe for opening and closing the pipeline, and a valve operating means connected to the control valve for opening and closing the pipe. And the valve actuating means comprises:
A lift tank connected to a liquid phase portion and a gas phase portion of a reactor pressure vessel, load supporting means for supporting the lift tank so that it can be moved up and down, and moving the lift tank upward when the load is reduced, a lift tank and a control valve. An emergency core cooling water injection device for a light water reactor, characterized in that it is arranged in an intervening state and is constituted by a valve drive section that opens the control valve when the lifting tank moves upward. 2. The emergency core cooling water injection device for a light water reactor according to claim 1, wherein the load supporting means of the valve actuating means is provided with an elastic member for receiving the weight of the lifting tank. 3. The emergency core cooling water injection device for a light water reactor according to claim 1 or 2, wherein a link mechanism for driving the control valve in the opening direction is arranged in the valve driving portion of the valve actuating means. 4. The emergency core of a light water reactor according to claim 3, wherein an elongated hole and a pin in an engaged state for delaying the movement in the opening direction are arranged at a connecting portion between the link mechanism and the control valve. Cooling water injection device.